Secret sharing is a technology that converts data into a distributed value obtained by dividing the data into a plurality of values and allows the original data to be reconstructed by using a given number of shares or more and does not allow the original data to be reconstructed from less than the given number of shares. Incidentally, a group of a plurality of values obtained by secret sharing is referred to as a distributed value and one fragment of the distributed value is referred to as a share.
If there is an inconsistency in shares held by calculation entities (hereinafter also referred to as parties), a problem of different reconstruction results depending on how a share is selected at the time of reconstruction arises. Thus, it is necessary to check whether or not there is an inconsistency in shares when the original data is reconstructed from the distributed value. Non-patent Literature 1 describes a technique of detecting an inconsistency in shares without passing a share to another calculation entity.